Download Extinction of Species

Extinction of Species
Extinction of Species
• 5 mass extinctions within the last 500 million years
• Dinosaurs survived the last mass extinction - lead to
evolution of some vertebrates
The Sixth Mass Extinction
• Homo sapiens are driving the next mass
extinction event
• 50,000 years ago when the first humans
spread out of Africa across to Asia, Europe and
Australia started this event
• Fire has been a catalyst in destroying
megafauna
Preventing extinction by preserving
genetic diversity
• Populations with reduced diversity face increased
risk of extinction – more efforts are focused on
conservation
• Large scale extinction:
– Not all species lost
– Larger organisms lost rather than smaller ones
– Larger populations more resilient than smaller ones
because of diverse gene pool and greater differentiation in
alleles to cope with selection pressures
Conservation Reserves
• Reserves used to protect endangered species
that are at risk from predation and human
influence
• Management of reserve must be carefully
considered
– Single large reserves or several small ones (SLOSS)
– Population size required for long term survival
Yellow-bellied glider
• Recovery plan set up by the Federal
Government has identified that:
– Gene flow of population is affected by
dispersal of gliders between areas of
habitat
– National reserve area can also be used to
study conservation of many other plants
and animals which many not survive in
smaller areas
Small Reserves and Wildlife Corridors
• Wildlife corridors link isolated
conservation areas
• Allows animals to move to new
locations when resources are
low, facilitates seasonal
migration and permit
interbreeding (good for gene
flow)
• Controversial idea as some
environmental experts claim
that green corridors are not
adequate for endangered
species
Questions
• Complete questions page 204
• Read the case study on pages 202-203 and
answer the questions
• This is all exam and test practice!!